It can be a bit of a concern when your truck pulls to one side.
Here we will have the answer to why this happens as well as what to do about it. We will cover why it may pull to the left or the right and much more.
Here’s a Quick Answer to Why a Semi Truck Pulls to One Side while Braking:
A semi truck typically pulls to one side i.e. either left or right, when there is an issue with the suspension or braking system that affects only one side of the truck. Poor wheel alignment and inadequate inflation of the tires can also cause the truck to pull to one side while driving.
Semi truck Pulls to the Right when Braking
If your semi truck is pulling to the right when braking, you may have the following issues:
Asymmetrical clamping of brakes – If your truck is pulling to the right when you brake, you should check the brakes are both equally tightened. If one brake is tighter than the other, you will find the vehicle plays up when you brake.
Left slack adjuster or S-cam rod – It could be the left slack adjuster is not braking the required amount or that the S-cam rod is broken. You may need to replace it or the S-cam rod.
Slipping brakes – It could also be that your left brake shoes have been exposed to oil and not holding enough traction. You may need to replace the wheel seals and shoes.
Semi Truck Pulls to the Left when Braking
The truck pulling to the left when you brake can be caused by some of the same issues as when it pulls to the right:
Damaged airline – Airlines can get damaged by stones during driving or become loose through vibration. Check them for air/oil leaks.
Worn out brake shoes/pads – The brakes on the other side may be wearing faster than the ones on the left of the truck. Try adjusting the brakes tight, then easing off 1/2 turn. Measure the slacks and take the vehicle for a run, then measure again.
Damaged U-bolts – It could be the U-bolts have come loose, damaged, or worn. It is recommended to visit a mechanic if you can not identify the problem.
The most probable cause of the vehicle pulling to one side when braking is bad brakes or a suspension system and if the vehicle pulls to one side while driving it is usually poor alignment or steering column issues.
Problems with the Semi Truck Braking System
In general, problems associated with uneven brake wear or even a stick break that occur on one side of the truck can lead it to pull towards one side.
Here is what brake system problems you should look out for if your truck pulls to one side:
Bad wheel cylinder
Brake cylinder failure – Bad wheel cylinders can cause brake failure altogether. If it is on one side of the truck, it may be the cause of the vehicle pulling to one side.
Symptoms – The brake pedal will feel spongy or slack. There will be a delay in response from your brakes. Check for leaking brake fluid. If your truck displays any of these issues.
Contaminated Brake Shoe or Pad
Brake line leak – If the brake shoes or pads get contaminated with oil from a leak in the system, you will firstly need to stop the leak by repairing the problem, then you may need to replace the brakes.
It would depend on how contaminated they are. If the brakes are worn, or the oil has been leaking a while it is better to replace them. Oil on the brakes will pick up dirt and debris.
The dirt or debris will act like sandpaper on the shoe or pads and cause wear and damage. Giving you uneven braking or worse. If the breaks are worth saving, use a brake cleaner.
Bad Brake Caliper
Bad break calipers – This can cause your brakes to wear out faster. They can cause the vehicle to pull to one side when braking or driving normally. They can also cause a high-pitch noise.
The breaks can wear unevenly. Check the inside of your tires for signs of a leak in the system. Listen out for any clanging noises. If the caliper has gone bad, you will need to replace it.
Make sure the fluids are topped up to the correct level.
Bad Brake Line
Bad brake lines – Could cause your truck to have defective brakes. The lines could have a leak. Chock the wheels of your vehicle and pump the air pressure up to 90 Ibs to check the air brakes.
How to check – Release the parking brake. If the pressure drops, then there is a leak in the system. Use a spray bottle with soap in it to find the leak. Check the lines on the firewall by listening for air leaks.
Make sure the lines are secure and not hanging down. Check the lines out to the brake chamber or secure and not leaking. If you need to replace brake lines, visit a workshop.
Bad Slack Adjuster or S-Cam
Slack adjuster – A bad slack adjuster can be temporarily adjusted to help you get from A to B. But will eventually cause you issues that could have been avoided. If you have bad slacks, replacing them is the safer option.
The slack adjuster is easy to fit and usually comes with instructions that you should follow to stay safe. The S-cam and Slack adjuster work together to aid the vehicle’s brake system.
Bad S-cam – A bad S-cam can affect the slack adjuster and vice versa. They are prone to rust. They can lose pressure and not adjust equally with the opposite side, causing uneven braking.
Other Causes of Semi Truck Pulling to One Side when Braking
If you have worn-out tires or a bad suspension on your semi truck, this could be another reason why it would pull to one side.
Worn tires – Bad tires on your truck can cause the vehicle to pull to one side. Uneven wear or pressure on the tires will cause a slight shift in alignment. To check the tires are correctly inflated, use a tire pressure gauge.
To check the tires are evenly worn, check them with a tire depth gauge. Keep all tires inflated to the required pressure, check the owner’s manual or the wall of the tire.
Suspension failure – Bad suspension on a semi truck can cause the vehicle to pull to one side. If one side of the truck’s shocks has been damaged but the other is working properly the truck can pull when braking.
It can also pull on rough terrain due to the suspension not working on one side. A broken leaf spring also on one side can cause the vehicle to pull to one side.
How long can you Drive with this Problem?
It is advisable to get the problem fixed as soon as possible to avoid further damage to the vehicle. You can drive the truck for some time with these problems.
The truck may be safe enough to drive for a week or a month depending on the severity of the issue, but the problem always worsens with prolonged driving.
Most times it isn’t worth the risk when you weigh out the safety aspect and the cost of repairs at a future date. As a result, it is recommended to fix the issue as soon as possible.
Is it Expensive to Fix?
The repair prices will vary depending on where you have the work done. What needs doing, and how long it will take them to do. Each workshop has its hour rates.
It could be as little as $200 and quickly escalate to over $800. If you repair it yourself, you will save a lot of money. You should take into account the price of the parts plus labor.
It is always better to visit a workshop with a good reputation. If you don’t know of any, ask a fellow truck driver.